Appendix: A refinement of the strong multiplicity one theorem for GL(2). (Appendix to R. Taylor). Dinakar Ramakrishnan — 1994 Inventiones mathematicae
Multiplicity one for the Gelfand-Graev representation of a linear group Dinakar Ramakrishnan — 1982 Compositio Mathematica
Modularity of the Rankin-Selberg L -series, and multiplicity one for S L ( 2 ) . Ramakrishnan, Dinakar — 2000 Annals of Mathematics. Second Series